(1) Field of the Invention
The present invention relates to an apparatus for controlling a call in a mobile communication system having lock, call restriction and accumulated call timer functions wherein the handset can be programmed.
(2) Description of the Related Art
The automobile has become indispensable in contemporary life, and comfort and convenience when driving has become increasingly important. To this end, vehicles can be provided with a mobile communication system which can be used as a telephone system.
An automobile equipped with a mobile communication system, e.g., a mobile radio telephone system, is called a mobile station, and this mobile station can communicate not only with a fixed telephone such as a telephone in an office or at home but also with another mobile station. This communication is established by radio waves between the mobile station and a land station, and transferred to a conventional telephone system at the land station.
In accordance with the increasing use of automobiles, the number of mobile stations has also increased, namely, not only private cars but also company cars or rental cars are now equipped with a mobile radio telephone system (are now mobile stations).
If the owner of the mobile station makes personal use of the mobile radio telephone, no problem arises, but when a person who is not the owner of the car equipped with the mobile radio telephone uses the telephone, for example when a employee uses the telephone system in a company car, or when an employee of a rent-a-car company uses the mobile telephone system after the rental car has been returned to the company, problems arise which can cause trouble for the owner of the mobile station.
Accordingly, some mobile stations are now equipped with an apparatus for restricting specific functions of the mobile radio telephone, for example, an apparatus for inhibiting an outgoing call, an apparatus for inhibiting a long distance call, or an apparatus for inhibiting memory dialling. Usually, the restriction of the outgoing call or the long distance call is used most in company cars, and the restriction of memory dialling or long distance calls is used most in private cars. The mobile radio telephones having those restrictions are divided into two types, a fixed type and a handset programmable type. The user of the mobile radio telephone cannot change the type of restriction in the fixed type, but in the handset programmable type, the user can change the type of restriction by inputting predetermined information from a dial or a keypad of the handset of the mobile radio telephone after an input of a registered security code. Therefore, the owner of the mobile station is faced with a choice between these two types when obtaining a mobile radio telephone from a telecommunication company.
Those two types are now explained in detail.
(1) Fixed type
There are, for example, four modes of restriction in the fixed type, as follows:
MODE 1: calls cannot be placed; PA1 MODE 2: calls cannot be received; PA1 MODE 3: long distance calls cannot be placed; PA1 MODE 4: no call restriction. PA1 MODE 1: calls cannot be placed: PA1 MODE 2: calls cannot be received; PA1 MODE 3: long distance calls inhibited; PA1 MODE 4: memory dialling inhibited: PA1 MODE 5: memory dialling and long distance calls inhibited; PA1 MODE 6: no call restriction.
The mobile radio telephone is provided with a transmitting and receiving unit and a call control unit. The control unit comprises a read only memory (ROM) called an ID (identification) ROM, wherein a telephone number and an identification number of the home mobile communication system to which the radio telephone is linked are stored. One of the MODE 1 to MODE 4 is stored in the ID-ROM when the mobile radio telephone is linked to the mobile communication system. The selection of the MODE is decided by the owner of the mobile station. Once one of the MODE 1 to MODE 4 is stored in the ID-ROM, that MODE cannot be changed by a user or the owner of the mobile radio telephone.
(2) Handset programmable type
There are, for example, six modes of restriction in the handset programmable type, as follows:
Note, the control unit is equipped with a random access memory (RAM) in addition to the ID-ROM. The ID-ROM is provided with areas for storing a telephone number, an identification number of the home mobile communication system to which the radio telephone is linked, the above-described six MODEs, a selection command for each of the six MODEs, and a security code for confirming that the person changing the MODE is allowed to do so. When the mobile radio telephone is linked to the mobile communication system, the selection of the MODE and the security code are made by the owner of the mobile station, and are written in the ID-ROM. The selected MODE is written in the RAM when the power is applied to the mobile radio telephone, and subsequently, the mobile telephone system is operated under the restriction of the MODE stored in the RAM. The MODE can be changed after an input of the security code by a user of the mobile telephone system.
Note that in the above mentioned mobile radio telephone, the ID-ROM for the fixed type and the ID-ROM for the handset programmable type are different. Namely, in the ID-ROM for the fixed type, only one of four MODEs is stored, and in the ID-ROM for the handset programmable type, all of six MODEs, a security code for mode change, and the MODE selection commands are stored. Here, the control unit must be equipped with a RAM for storing the MODE selection.
Accordingly, the manufacture of mobile radio telephones must produce separate control units for the fixed type and the handset programmable type, which increases the manufacturing cost of the mobile radio telephone.